Reigning NFC West champion San Francisco, which lost in overtime of the NFC title game to eventual Super Bowl champion New York, announced the moves Monday, a day before free agency begins. The team also worked out veteran wideout Randy Moss.

49ers CEO Jed York said the team needs "someone to stretch the field." The Niners are working to re-sign quarterback Alex Smith, with York saying they've had "good conversations back and forth."

Brock has appeared in 14 games in two seasons, while Grant became a key fill-in last season on Vic Fangio's defense while All-Pro linebacker Patrick Willis nursed a hamstring injury.